To reiterate my earlier comment, mobile malware is a thing. Example. It’s documented as done by many countries (US included), and the border guard does not have to be a “genius”, as they are provided all the hardware and software.
Wiping could help (by removing passwords/credentials to access cloud data), but not if you proceed to reveal that password, plus the phone remains hacked.
ETA sorry for the bad news, but don’t transfer private data over the border this way! It is unprofessional. If it’s just pictures of your dog and your kids’ phone numbers then it may not matter, of course.
Seems the more that someone has crossed international borders (particularly in the past 10 years) the less likely they are to puff about their “rights” and “I am personal friends with Alan Alda’s accountant!” and “HOW DARE YOU SIR!!1!” and instead just shrugging, sighing quietly, gritting your teeth and quietly complying with all the bullshittaree hoops they tell you to jump thru.
Try walking around any random airport in Western Europe, where there are dozens of young, 20-something men in uniform with sub-machiene guns slung across their chest and start smacking your lips and giving the big wink and grandly crowing about butt-fucking and then get back to us.
I crossed the Canadian border with a flip phone. The only one I have. They asked me why it was off. I said it doesn’t have airplane mode. They asked me for the password. I said open up and push and hold the “end” button. They asked me where the files were stored. I said as far as I knew, the only files on it were contacts.
The one person I have spoken with myself who had her phone searched by CBP was a client, on suspicion of coming to work illegally. As it turned out, that time CBP was correct. She was coming on the Visa Waiver and was sent back on the next flight.
Did the contents of her phone prove she was coming to work illegally? Or was searching her phone just a bit of additional harassment after they determined she was persona non grata?
No issues with the phones, but we crossed the border 3 times last June (we were staying on the Vermont side of the border for a few days, and made several day trips, then we spent a few days up in Quebec).
The US agents were more uptight each time than any of the Canadian agents.